As is well known in the art, the human heart has four valves that control blood flow circulating through the human body. Referring to FIGS. 1A and 1B, on the left side of the heart 100 is the mitral valve 102, located between the left atrium 104 and the left ventricle 106, and the aortic valve 108, located between the left ventricle 106 and the aorta 110. Both of these valves direct oxygenated blood from the lungs into the aorta 110 for distribution through the body.
The tricuspid valve 112, located between the right atrium 114 and the right ventricle 116, and the pulmonary valve 118, located between the right ventricle 116 and the pulmonary artery 120, however, are situated on the right side of the heart 100 and direct deoxygenated blood from the body to the lungs.
Referring now to FIGS. 1C and 1D, there are also generally five papillary muscles in the heart 100; three in the right ventricle 116 and two in the left ventricle 106. The anterior, posterior and septal papillary muscles 117a, 117b, 117c of the right ventricle 116 each attach via chordae tendinae 113a, 113b, 113c to the tricuspid valve 112. The anterior
and posterior papillary muscles 119a, 119b of the left ventricle 106 attach via chordae tendinae 103a, 103b to the mitral valve 102 (see also FIG. 1E).
Since heart valves are passive structures that simply open and close in response to differential pressures, the issues that can develop with valves are typically classified into two categories: (i) stenosis, in which a valve does not open properly, and (ii) insufficiency (also called regurgitation), in which a valve does not close properly.
Stenosis and insufficiency can occur as a result of several abnormalities, including damage or severance of one or more chordeae. Stenosis and insufficiency can also occur concomitantly in the same valve or in different valves.
Both of the noted valve abnormalities can adversely affect organ function and result in heart failure. By way of example, referring first to FIG. 1E, there is shown normal blood flow (denoted “BFN”) proximate the mitral valve 102 during closure. Referring now to FIG. 1F, there is shown abnormal blood flow (denoted “BFA”) or regurgitation caused by a prolapsed mitral valve 102p. As illustrated in FIG. 1F, the regurgitated blood “BFA” flows back into the left atrium, which can, if severe, result in heart failure.
In addition to stenosis and insufficiency of a heart valve, surgical intervention may also be required for certain types of bacterial or fungal infections, wherein the valve may continue to function normally, but nevertheless harbors an overgrowth of bacteria (i.e. “vegetation”) on the valve leaflets. The vegetation can, and in many instances will, flake off (i.e. “embolize”) and lodge downstream in a vital artery.
If such vegetation is present on the valves of the left side (i.e., the systemic circulation side) of the heart, embolization can, and often will, result in sudden loss of the blood supply to the affected body organ and immediate malfunction of that organ. The organ most commonly affected by such embolization is the brain, in which case the patient can, and in many instances will, suffer a stroke.
Likewise, bacterial or fungal vegetation on the tricuspid valve can embolize to the lungs. The noted embolization can, and in many instances will, result in lung dysfunction.
Treatment of the noted heart valve dysfunctions typically comprises reparation of the diseased heart valve with preservation of the patient's own valve or replacement of the valve with a mechanical or bioprosthetic valve, i.e. a prosthetic valve.
Various prosthetic heart valves have thus been developed for replacement of natural diseased or defective heart valves. Illustrative are the tubular prosthetic tissue valves disclosed in Applicant's U.S. Pat. Nos. 9,044,319, 8,709,076 and 8,790,397, and Co-Pending U.S. application Ser. Nos. 13/560,573, 13/804,683, 13/480,347 and 13/480,324. A further tubular prosthetic valve is disclosed in U.S. Pat. Nos. 8,257,434 and 7,998,196.
Heart valve replacement requires a great deal of skill and concentration to achieve a secure and reliable attachment of a prosthetic valve to a cardiovascular structure or tissue. Various surgical methods for implanting a prosthetic valve have thus been developed.
The most common surgical method that is employed to implant a prosthetic valve (mitral or tricuspid) comprises suturing a circular synthetic ring of a prosthetic valve to the annular tissue of the heart where a diseased valve has been removed.
A major problem associated with prosthetic valves is tissue valves with gluteraldehyde cross-linked leaflets will calcify and deteriorate over time.
Another problem is mechanical valves will require anticoagulation agents, such as Coumadin, which can cause side effects in high doses, such as uncontrolled bleeding.
Another problem is the valves do not remodel into normal tissue capable of regeneration and self repair.
Another problem is many valves must be placed with open heart surgery while the patient is on a heart-lung machine.
There is thus a need to provide improved prosthetic tissue valves and methods for attaching same to cardiovascular structures and/or tissue that maintain or enhance the structural integrity of the valve when subjected to cardiac cycle induced stress.
It is therefore an object of the present invention to provide improved prosthetic tissue valves and methods for implanting same that overcome the drawbacks and disadvantages associated with conventional prosthetic atrioventricular valves.
It is another object of the present invention to provide improved methods for securely attaching prosthetic tissue valves to cardiovascular structures and/or tissue.
It is another object of the present invention to provide prosthetic tissue valves having means for secure, reliable, and consistently highly effective attachment to cardiovascular structures and/or tissue.
It is another object of the present invention to provide extracellular matrix (ECM) prosthetic tissue valves that induce host tissue proliferation, bioremodeling and regeneration of new tissue and tissue structures with site-specific structural and functional properties.
It is another object of the present invention to provide ECM prosthetic tissue valves that induce adaptive regeneration.
It is another object of the present invention to provide ECM prosthetic tissue valves that are capable of administering a pharmacological agent to host tissue and, thereby produce a desired biological and/or therapeutic effect.